Flying ram cutoff machines, and drive systems therefor, are well known in the art. Machines of this type include a ram swingably mounted on a stationary bed and a die set reciprocably mounted on the bed. An accelerator reciprocates the die in synchronism with the workpiece and is cammed by the ram to selectively clamp the workpiece immediately prior to and during a cut. A drive system coupled with a source of power, such as an electric motor and flywheel, produces orbital swinging movement of the ram in synchronization with the movement of an elongate workpiece which continously travels through the die set.
It is generally desirable to orient the ram in a horizontal plane in connection with the severing of a workpiece having a circular cross section. Cutoff machines of this general type are disclosed in U.S. Pat. Nos. 3,288,011 and 3,288,012. As shown in the disclosures of both of these prior patents, a drive system for operating the horizontal ram includes a motor, flywheel, and clutch assembly mounted on the rear of the machine which power a drive shaft that extends perpendicular to the longitudinal axis of the workpiece. In those applications wherein high ram pressures must be developed to sever relatively thick workpieces, it is necessary to drive the ram at least at two locations using crank assemblies coupled to a pair of power take-offs from the main drive shaft. As shown in U.S. Pat. No. 3,288,012, the output of the main drive shaft is delivered through a pinion gear to a pair of crank gears which, in turn, rotate take-off shafts that drive the crank assemblies. Although this arrangement is perfectly satisfactory in terms of results, the crank gears are relatively massive and therefore not only displace a considerable amount of volume but are relatively expensive to produce. More importantly, however, in order to drive rams of extended length, it is necessary to either increase the pitch diameter of the pinion and crank gears, or various idler gears must be employed in order to transmit power from the drive shaft to the take-off shafts. These alternatives have the disadvantage of increasing the number of gear components which must be maintained in inventory and/or, increase the number of components, and therefore overall costs, of the machine. Additionally, the relatively massive crank gears substantially increase drive train inertia thereby making it more difficult (and most costly) to control synchronism of the ram.
In the case of workpieces having a square or otherwise angular cross section configuration, it is desirable to employ an inclined ram in order that the die set and associated severing blade may be likewise inclined at a desired attitude to improve the quality of cut. This necessitates specially configured drive train components. Consequently, alternate drive systems have been developed for powering inclined rams as exemplified by the machine disclosed in U.S. Pat. No. 3,272,433. As shown in this last-mentioned patent the motor, flywheel, brake and clutch are disposed at one end of the machine and power a drive shaft which extends essentially parallel to the longitudinal axis of the workpiece. Power take-off from the main drive shaft is accomplished through a series of spur gears and crank arms which are relatively complex in their arrangement. This type of drive system is incompatible with the requirements of a horizontal ram machine, consequently, the components of drive systems for the horizontal and inclined ram machines are not readily interchangeable.
A further shortcoming of prior art drive systems common to both the horizontal and inclined rams involves the phenomenon of backlash through the drive system created by cumulative manufacturing tolerances in the drive train gears. Backlash in prior art systems could be controlled only by altering the thicknesses of certain gear teeth of the drive gears. This approach to the problem is naturally time consuming and therefore costly from a labor as well as from a material standpoint. Excessive backlash in prior art drive systems sometimes results in a loss of operating synchronism between the crank assemblies thereby substantially increasing drive train wear and posing a substantial risk of component failure due to the excessive stresses.
Accordingly, it is an important object of the present invention to provide a drive system which not only reduces the number of drive train components but allows such components to be interchangeably employed in connection with rams of either the horizontal or inclined type.
A further important object of the present invention is to provide a drive system of the type mentioned above in which particularly long rams may be driven at substantially spaced locations without the need for altering pitch diameter of the drive gears or employing idler gears or the like. In connection with this object of the invention, the present drive system significantly reduces overall inertia in the drive train thereby reducing inertial stress on the clutch and brake of the system.
Another object of the present invention is to provide a drive system of the type mentioned above in which backlash through the drive train may be effectively and simply controlled.
A still further object of the present invention is to provide a drive system as mentioned above which employs a pair of bevel gears respectively connected to a drive shaft and a pair of take-off shafts at spaced locations along the drive shaft.